Safety fuse device



May 21, 1935. J. STONE SAFETY FUSE DEVICE Original Filed Sept. 9, 1929 lllllllllllllllllllll J erzfr: r J 6 fltoize Reissued May 21, 1935 UNITED STATES PATENT osrlcs manufacturing 111., a corporation of New York Company, Uhiesroi Original 'No. 1,224,415, dated septemhor 22. 1931,

Serial No. 391,450. September 9. 1929. Application [or reissue September 21, 1933, Serial 9 Claims.

The present invention relates to electrical safety ilise devices and has for its object the provision of a fuse plug connection which prevents electrical connections being made in the electric circuit by improper means, such as the use of metal slugs, @{wlrea tinioils, oversize'fuse plugs, or the The present device is so constructed, that the which will be herein more .fully described may be used with the ordinary 'iuse mocks now in use. while at the same time the mac plugs now in may not be used with any iuse blocks to which my improvements have been applied Iiioi'dertouse anyiuseblockhavingmyinmention added thereto. a special type of tuseplug is required, the nature of which will also be fully assented in this specification.

' lite adaptability army invention for use without -tlianging 01 parts, in connection with the arm type or time blocks in common use, will readily'be understood from the description, and it will be at once seen that thisieature constitutes one, in my invention. 7 Two'lmportant features-oi the presentinvention are the following, to wit. the modification of the bottom endoi an ordinarygiuse plug, bytheaddion contact pin of considerable length, and addition of a having a concentric electing ring preferably formed integral thereand secondly, a special washer, called an having a surface formed complementary 301%,):

h ass at the fuse plugandprovided with a perforation adapted .to permit the contact pin to pass therethrough.

nae use at the combined features just named, 'proiddes a means of preventing surreptitious use at electrical fuse block plug, and electrical circuit, by the'use oi slugs, tinioils, wires, etc.

m the drawing forming part or the present ,taflgn.

-me3 isavertlcal partialsection or the base ,60 the tune plug, and the adapter with associated maisatopplanviewoithefuseplugs rigure5isabottomviewot the use-plug. m6 isaplanview i? m of the special washer or .(Cl. zoo-11!) Figure '1 is a side view of Figure 6. I

Figure 818 a plan view of a locking spring ring used in connection with the adapter.

Figure 9 is asideview oithe ring shown in Figure 8. v

In the drawing, thenumeral 1 ,indicates a por celain base, called the fuse block, or the form shown, provided with the usual necessary parts, such as the ingoing or r eoer connection 2, and the outgoing branch circuit connection a, the cupshaped recess 1, with a metal ferrule 5 seated therein, The connection 2, leads by means or the bent plate 8 to the contact pin 1, shown clearly in Figure 1.

The connection 3 is provided with a yoke I,

which is accommodated within the ferrule 5, and

lies on the bottom 8 thereof. Above the yoke is an insulating thin washer It, and a metal holding washer i1, and it is seen that the contact screw 1 passes through the cluster of parts just named, and down through the porcelainiuse block to the bent plate 6, and is secured thereto, in the usual fashion. It will be noted the head 12 of the contact screw 1 is flattened somewhat, so that it seats nicely in the bottom recess I3 of the special "Micartw washer ,see Figure 8. r

This special wash It, or adapter is made preferably of a hard, non-conductive, material, such as compounded substances like Mlcarta, which is composed of mica and other substances, commonly used in the trade. The P 9 8 or requiring substantially hard material, will be more fully described below.

The cross-sectional shape or form or the adapter ll is-shown in Figure 3, and a. plan view in Figure 6, in which it is seen that a concenthe recess I5 is formed in the top 01! same and a. perforation l6 passes through the center, ada ted to receive the fuse plug contact'pin H. on the bottom or the adapter is a depression or recess vIt, before described, and on its periphery, is a groove l8, adapted to receive the spring keeper, or holding wire I. It will be seen from Figures 6 to 9 inclusive, that a small vertical holding pin ;is' inserted in the perforated ends' 2|, and 12 of the spring wife 19, which ends are slightly flattened to accommodate the double thickness to the groove 18 of the adapter. This pin is only for a temporary purpose, to wit, to hold the spring keeper or wire in a compressed position within the periphery of the adapten'as shown in Figure I. It will be seenthatwhilethespringwirelsisincompressed position, that the adapter can be insorted freely within the ferrule i, and placed at the bottom thereof, on top of the head l2, of the contact screw 1, with the former in the recess l3. When the adapter is in this position the pin 201s withdrawn, and the wire l9 springs outward,and locksitself in the Ewes 23 of the ferrule 5,, and theadapter then re; moved without destroying ferrule 5. The purpose of this is toenable the ordinary ferrule of; the fuse block to be usedwith my invention,

without any changes being made. It is-evident that this is a very importantfeature. of the device, in that the present fuse blocks can be used without changes in their construction. I The fuse plug base, which is newly formed in the present invention, consists ofthe; following. The portion of the 'fuse plug 24, which is above the corrugated projectingdisc 25, is substantially the same as in common use, except that the length of the plug is shortened. Mounted on the plug, .is-the plug disc 25, which is formed preferably of the same material as the adapter, to with of ,a hard, insulating pressed substancaor compound, which'has been made under hydraulic or other great pressure. On the face of;-the disc 25,,ismounted a concentric projecting ring 25, preferably made integral therewith and also formed complementary in shapewith the recess iii of the adapter before described, so it is evident the, fuse plug base flts snugly into the upper faceof theadapter, and the'contact pin passes through thecenter perforation IG of thej'latter and makes contact with the top l2 of the'contact screw 1, when the fuse plug2l is screwed home" in the threads of the ferrule. contactpin may be mounted in any suitable'rigid manner to the upper portion of the fuse plug 24, and the latter has the usual fusible element 21 within it for carrying the cur-, rent from thecontact pin to the fuse 28, which in turn leads same to the metal screw threads covering the plug at 30, which in turn contact the threads of the ferrule 5. I,From ferrule B it reaches theyoke 8 and the branch circuit con,-

nection 3. H c

'Fromwhat has been said it is seen that electric current comes in through the feeder connection 2, passes, through bent plate 6, into contact screw 1. Then to the contact pin l1, and

through the parts just described branchcircuit connection 3. M

With reference to the surreptitious useof the device, it is quite evident that coins cannot be used in any manner to form aconnection electricallybetween the head l2 of the contact screw 7, and walls of the ferrulel', which is necessary in order to close the circuit from connections above to the Should a piece of wire be wrapped around the contact pin ll of the fuse plug, in such a manner as to extend diametrically across the base of the fuse plug, to make a contact with the ferrule 5, and the pliig then screwed "home, it will be found thatv if the wire is heavy enough to'resist the mutilating effect of the complementary enough to conform to the shape of the complementary corrugations of the plug and adapter, it will be partially sheared, and so mutilated, that it will not have a current carrying capacity of over the fifteen amperes, the usual safe carrying. capacity of the electrical system, and in this case will not injure the same.

1. In a safety fuse device, a fuse block having a feeder connection. and a branch circuit connection, a ferrule mounted in the block, an adapter having a perforated center, a concentric recess formed in the upperface of the adapter, and a peripheral recess formed in the adapter, a spring locking wire adapted to fit in the peripheral recess, and lock the adapter within the ferrule, a fuse plug having a centrally disposed contact pin therein, a fuse plug disc having a concentric projecting ring thereon formed complementary to the concentric adapter recess, a contact screw mounted in the fuse block, means connecting the contact screw with the feeder connection, and means connecting the contact pin with the branch circuit connection. I

2. In a safety fuse device, an adapter having a central perforation, a concentric recess formed in its upper face, a centrally disposed recess formed in the bottom of said adapter, a peripheral groove in the periphery of the adapter, a spring ring mounted in the peripheral groove, andmeans for holding the spring ring within the peripheral limits ofthe adapter.

3. In a safety fuse device, an adapter having a central perforation therein, a concentric recess in its uppersurface, a recess in itsbottom face, a peripheral groove formed on the outer walls of the adapter, a spring ring mounted in thegroove,

a fuse plug having a central contact pin, adapted to pass through the central perforation of the adapter, and a concentric projecting ring on the bottom of the fuse plug'formed complementary to the concentric recess of the adapter.

4.In a safety fuse'device, a ferrule, having a number of screw threads formed therein, an adapter having a peripheral groove and a pair of alined holes therethrough, a split spring ring having tapered overlapping ends, and a pair of aline-- able holes therethrough mounted in the groove, and holdingand releasing means comprising a holding pin adapted to pass through the holes in the adapter and split ring for holding thesjiiing ring within the periphery of the adapter while 'the same isbeing mounted in the ferrule, and for releasing the ends of said ring whenthe latter is in desired position within the ferrule, i

5. In a safety fuse device, a fuse block having incoming and out-going'electrical circuit connections, a contact screw having connections with the incoming electric circuit connection, an adapter having a central perforation therethrough, a concentric recess in the upper face'of the adapter, a recess in the adapter for accommodating the head of the contact screw, 2. ferrule on the fuse block having threads formed therein,

a fuse plug having a contact pin mounted therein, a disc on the base of the fuse plug havin a.

concentric projection thereon, formed com ementary to the concentric recess of the adapter,

for permitting the contact pin to form an electrical connection with the contact screw, means for locking the adapter in the ferrule grooves, and means connecting the contact pin with'the out-going circuit connection. r

6. In a safety fuse device, a splitspringring, having tapered ends, adapted to slide uponeach 7 other, and having perforations in said ends adapted to be in alignment when the spring is in a contracted position, and a holding pin adapted to pass through the perforations, and hold the spring in contracted position.

7. In a safety fuse device, an adapter, having a peripheral recess formed therein, and a pair of perforations in alignment with each other, a split spring ring, having a pair of perforations therein which can be aligned with each other and the perforations in the adapter when the spring ring is in a contracted position, and a pin adapted to pass through all the perforations, and hold the spring ring in contracted position, within the peripheral limits of the adapter circumference.

8. In a safety fuse device, a fuse block having incoming and outgoing electrical circuit connections, a contact element having connections with the incoming electrical circuit connection, an adapter having a central perforation therethrough, a concentric recess in the upper face of the adapter, a recess in the adapter for accommodating the head of said contact element, a ferrule on the fuse block having threads formed therein, a fuse plug having a contact pin mounted therein, a disc on the base of the fuse plug having a concentric projection thereon, formed complementary to the concentric recess of the adapter, for permitting the contact pin to form an electrical connection with the contact element, means for locking the adapter in the ferrule grooves, and means connecting the contact pin with the outgoing circuit connection.

9. In a safety fuse device, a fuse block having incoming and outgoing electrical circuit connections, a contact element having connection with one of said electrical circuit connections, an adapter having a central perforation therethrough a concentric recess in the upper face of the adapter, 9. ferrule on the fuse block having threads formed therein, a fuse plug having a contact pin mounted therein and a base having a concentric projection thereon, formed complementary to the concentric recess of the adapter, whereby to permit the contact pin to form an electrical connection with said contact element, means for looking the adapter in the base of said fuse block, and

means connecting the contact pin with the other wire of said electrical circuit connections.

JESSE STONE. 

